Stock? Hi Pressure? Hi Volume?

-
S

Sanguine

Well-Known Member
Joined
Aug 11, 2006
Messages
227
Reaction score
0
Location
Amherst, NS
Building a 340 for my '75 duster, strictly for street use...before I had a stock pump with a hi pressure spring installed
I know you lose HP with the high volume...
Do I really need anything but the stock pump?
She wont see anymore than 6500 RPM and then not very often...
Also going to run a 8 qrt Moroso pan...anyone have one of these installed? I was wondering about the ground clearance? cant be much worse than the header clearance
 
Personally, I'd run a HV pump. You have the extra capacity so sucking the pan dry isnt going to be a concern. Just my personal preference.
 
Sanguine said:
Building a 340 for my '75 duster, strictly for street use...before I had a stock pump with a hi pressure spring installed
I know you lose HP with the high volume...
Do I really need anything but the stock pump?
She wont see anymore than 6500 RPM and then not very often...
Also going to run a 8 qrt Moroso pan...anyone have one of these installed? I was wondering about the ground clearance? cant be much worse than the header clearance
Click to expand...

Had a Moroso 8qt pan on the 340 in my '73 Duster. Won't do that again! Sump is 10" + and not street friendly (at least around my neck of the woods).
 
Go with the new street/strip Milodon pan and pickup - 7 qts I believe.
I went with the high volume and have way to much pressure 90+ until it gets really hot - then at idle drops to 60. For you need go wirth a stock pump - Melling if you can get one.
 
I also have to much pressure with the High volume pump on my 360 engine, causing it to leak around the oil filter gasket during each pass. 100+ lbs at high rpms, 65 idleing hot, with 30 wt oil. I 've tried several different filters and even reinstalled the 90 degree adapter. I was thinking about going back with stock pump. I know several people that run stock pumps in their race engines with no problems.

Mrmopartech could you explain how you set the spring for 60 lbs on the small block pump with out having to pull the pan more than once. Thanks
 
I measured the Moroso pan for depth compared to the stock pan and its 2.5" deeper...
 
As I mentioned earlier, I won't make the mistake of putting the Moroso pan on mine again. Nice big dip in the road + too much speed = one smashed oil pan.
 
If you are keeping the bottom end clearances close to stock, just run a stock pump. Even that can pump 4 qts into the valve covers faster than it can drain back! Stock small blocks were never known for under oiling under anything less than really brutal use. If you run a high volume with a stock pressure spring, you are bypassing almost all the time. If your pressure exceeds the bypass pressure then you are delivering not only more oil than engine can use, but more than the bypass can dump back into the pan! Oil filters will either internally bypass (and not filter) or leak. And it takes an obscene amount of power to pump oil at that presssure! Whats the point in buying an "accurate" timing set if your cam is going to see up to 10 degrees of twist due to massive oil pump load. Yeah, that twist is at the distributor end! More crankshafts have been trashed due to oil pump drive shaft failure than starvation.

Go out and (have a friend) watch your oil presure gauge as you make a max effort acceleration to top speed. You want 10 PSI per 1000 RPM. Asl long as you dont see a high RPM drop, you are fine.

Also consider oil control. If you have that big pump slinging oil everywhere, how much makes it past the rings? It sure dont take much oil to cause massive detonation. I'd buy a scraper and tray and stick with a stock pump on the street.
 
I run a moroso pan on my duster with drag tosion bars in the front. I never had a ground clearance ussue with it. I ran high volume pumps on the street and had pressure to high until its warms up. From what you said your engine is use the stock pump. My last street engine i built i used a 70 340 motor 30 over 509 mp cam stock valve train ,stock oil pump ,pan, pick up. turned 6500 rpm at strip for 100 plus passes at the track. with no problems. Harry
 
I have a HV Mellings pump, and a stock 5 qt pan with custom baffles welded in.

I never see more than about 60psi at highway RPMs.
 
superdart said:
I have a HV Mellings pump, and a stock 5 qt pan with custom baffles welded in.

I never see more than about 60psi at highway RPMs.
Click to expand...

about the same here, i have a stock pan. hv melling pump. half groove main bearings, i never see over 75psi cold with 15w-40. and not over 60lbs hot
 
I vote for the stock pump too. No point in putting extra load on an engine when it provides no benifit.

For 90% of the applications using a HV pump is in the same category as over camming or over carbing. "If it's bigger it must be better."
 
I have run stock pans with high volume pumps. After a hard run i could hear my valve train. After a summer of this i spun #7 rod bearing. Use a stock pan with a stock pump you will have no problems. Harry.
 
Harry, we agree.
There really is no need for an HV/HP pump, even in the harshest of conditions.
I've found through many trials and errors, some my own, some not, that the closer you keep to 70 PSI as a MAXIMUM pressure (6500-7000 RPM max engine speed), with an idle pressure of around 20, normal engine temp of 190-200 degrees, there will be no problems.

There is such a thing as too much oil pressure, remember, most of the oil passages in an engine are sharp bends and sharp bends tend to cause oiling issues, which compound as oil pressure and volume goes up.

While the guage reads high, 80 psi plus, the oil can actually do damage to bearings at high pressure, this is called bearing erosion.

Stock pump + Stock pan = no oiling issues.

Mark.
 
You must log in or register to reply here.
-

Back
Top